Method and Apparatus for Generating Phosphor Film with Textured Surface

ABSTRACT

An optical device deploring a phosphor layer having a textured surface to improve output of visual light is disclosed. A light emitting device includes a solid state light emitter and a phosphor layer. The solid state light emitter, for example, is configured to convert electrical energy to optical light. The phosphor layer includes a first surface and a second surface, wherein the first surface, for example, is the top surface while the second surface is the bottom surface. The phosphor layer is disposed over the solid state light emitter for generating luminous light in response to the optical light. The first surface of the phosphor layer, in one embodiment, is configured to include a texture, which has similarly shaped uniform configurations, capable of reducing total internal reflection.

PRIORITY

This patent application is a continuation of U.S. patent applicationSer. No. 12/209,638, filed Sep. 12, 2008, entitled “Method and Apparatusfor Generating Phosphor Film with Texture Surface,” the disclosure ofwhich is incorporated herein by reference.

FIELD

The exemplary aspect(s) of the present invention relates to lightingdevices. More specifically, the aspect(s) of the present inventionrelates to solid state light emitting devices.

BACKGROUND

As light output from LEDs or solid state light sources improve quicklyand become increasingly viable alternatives, conventional lightings suchas incandescent lamps and fluorescent lamps will soon be replaced withenergy-efficient LEDs. A conventional LED is small and energy efficientwith a good lifetime. Various commercial applications of LEDs, such astraffic lights, automobile lightings, and electronic billboards, havealready been placed in service.

An important aspect of solid state optical property in applying generalillumination is total luminous flux, or overall visible lighting output.A problem associated with lighting output from a solid state lightemitter or LED is the total internal reflection (“TIR”) phenomenon. Whena light ray or beam crosses between two different materials with twodifferent medium having different refractive indices, the TIR phenomenonoccurs. For instance, when light ray strikes boundaries between twolayers having different materials with different refractive indices, thelight ray may be partially refracted at the boundary surface, andpartially reflected through a layer.

The occurrence of the TIR phenomena within solid state lighting devicesnormally impacts and reduces luminous efficiency. In some instances, theTIR phenomena can generate heat from the reflective light. For example,when the blue optical light generated by LED strikes at an area ofrelatively flat surface of a phosphor layer, a TIR phenomenon betweenthe phosphor layer and the LED may occur depending on the angle of theoptical light with respect to the surface of the phosphor layer.

SUMMARY

An optical device employing a phosphor layer having a textured surfaceto improve output of the visual light is disclosed. A light emittingdevice includes a solid state light emitter and a phosphor layer. Thesolid state light emitter, for example, is capable of convertingelectrical energy to optical light. The phosphor layer has a firstsurface and a second surface, wherein the first surface, for example, isthe top surface while the second surface is the bottom surface. Thephosphor layer is disposed over the solid state light emitter forgenerating luminous light in response to the optical light. The firstsurface of the phosphor layer, in one embodiment, is configured toinclude a textured surface, which has similarly shaped uniformconfigurations, capable of reducing total internal reflection (“TIR”)between the solid state light emitter and the phosphor layer.

Additional features and benefits of the exemplary aspect(s) of thepresent invention will become apparent from the detailed description,figures and claims set forth below.

BRIEF DESCRIPTION OF THE DRAWINGS

The exemplary aspect(s) of the present invention will be understood morefully from the detailed description given below and from theaccompanying drawings of various aspects of the invention, which,however, should not be taken to limit the invention to the specificaspects, but are for explanation and understanding only.

FIG. 1 is a cross-section view of an optical device including a phosphorlayer having a textured surface in accordance with an aspect of thepresent invention;

FIGS. 2( a-b) is a cross-section view of an optical device having aphosphor layer with a textured surface and a light extracting layer inaccordance with an aspect of the present invention;

FIG. 3 illustrates an exemplary lighting device having a phosphor layerwith a textured bottom surface in accordance with an aspect of thepresent invention;

FIG. 4 is a cross-section view of an example of an optical deviceincluding a phosphor layer with two textured surfaces in accordance withan aspect of the present invention;

FIG. 5 is a cross-section diagram illustrating an optical device capableof generating natural white and warm white light using a texturedphosphor film in accordance with an aspect of the present invention;

FIG. 6 is a cross-section diagram illustrating an optical device capableof generating natural white and warm white light using textured phosphorislands in accordance with an aspect of the present invention;

FIGS. 7( a-d) illustrate examples of textured configuration for aphosphor layer in accordance with an aspect of the present invention;

FIG. 8 illustrates an optical device having multiple solid state lightemitters using a textured phosphor layer in accordance with an aspect ofthe present invention; and

FIG. 9 is a flowchart illustrating a process of manufacturing a lightingdevice having a textured phosphor layer in accordance with an aspect ofthe present invention.

DETAILED DESCRIPTION

Aspect(s) of the present invention is described herein in the context ofa method, device, and apparatus of improving luminous output from asolid state light emitter using textured surface.

Those of ordinary skills in the art will realize that the followingdetailed description of the exemplary aspect(s) is illustrative only andis not intended to be in any way limiting. Other aspects will readilysuggest themselves to such skilled persons having the benefit of thisdisclosure. Reference will now be made in detail to implementations ofthe exemplary aspect(s) as illustrated in the accompanying drawings. Thesame reference indicators will be used throughout the drawings and thefollowing detailed description to refer to the same or like parts.

In the interest of clarity, not all routine features of theimplementations described herein are shown and described. It will, ofcourse, be understood that in the development of any such actualimplementation, numerous implementation-specific decisions may be madein order to achieve the developer's specific goals, such as compliancewith application- and business-related constraints, and that thesespecific goals will vary from one implementation to another and from onedeveloper to another. Moreover, it will be understood that such adevelopment effort might be complex and time-consuming, but wouldnevertheless be a routine undertaking of engineering for those ofordinary skilled in the art having the benefit of this disclosure.

It is understood that an aspect of the present invention may containintegrated circuits that are readily manufacturable using conventionalsemiconductor technologies, such as, CMOS (complementary metal-oxidesemiconductor) technology, MEMS (Microelectromechanical systems)technology, or other semiconductor manufacturing processes. In addition,the aspect of the present invention may be implemented with othermanufacturing processes for making optical as well as electricaldevices.

Those of ordinary skills in the art will now realize that the devicesdescribed herein may be formed on a conventional semiconductor substrateor they may as easily be formed as a thin film transistor (TFT) abovethe substrate, or in silicon on an insulator (SOI) such as glass (SOG),sapphire (SOS), or other substrates as known to those of ordinary skillsin the art. Such persons of ordinary skills in the art will now alsorealize that a range of doping concentrations around those describedabove will also work. Essentially, any process capable of forming pFETsand nFETs will work. Doped regions may be diffusions or they may beimplanted.

The present aspect(s) of the invention illustrates a lighting device,which uses a phosphor layer having a textured surface to improve theoutput of visual light. A lighting device includes a solid state lightemitter and a phosphor layer. The solid state light emitter, forexample, is configured to convert electrical energy to optical light.The phosphor layer has a first surface and a second surface, wherein thefirst surface, for example, is the top surface while the second surfaceis the bottom surface. The phosphor layer is disposed over the solidstate light emitter for generating luminous light in response to theoptical light. The first surface of the phosphor layer, in oneembodiment, is configured to include a texture, which has similarlyshaped continuous uniform configurations capable of reducing totalinternal reflection (“TIR”) between the solid state light emitter andthe phosphor layer.

FIG. 1 is a cross-section view of an optical device 100 including aphosphor layer having a textured surface in accordance with an aspect ofthe present invention. Device 100 includes a substrate 102, a solidstate light emitter 104, a phosphor layer 108, and walls 110. Walls 110are used to separate optical device 100 from other components such asneighboring optical devices. Substrate 102, for example, is furthercoupled to a circuit board, not shown in FIG. 1. Device 100, in anaspect, etches a textured surface over phosphor layer 108 to reduce thephenomenon of TIR. The total luminous lighting output for device 100 isenhanced when TIR is minimized. It should be noted that the underlyingconcept of the exemplary aspect(s) of the present invention would notchange if one or more blocks (or layers) were added to or removed fromdevice 100.

Solid state light emitter 104, in one example, is a light emitting die,which can be manufactured by a semiconductor fabrication process. Afunction of solid state light emitter 104 is to convert electricalenergy to optical light. Solid state light emitter 104 can be a lightemitter diode (“LED”), which is capable of transferring electricalenergy to optical energy via a biased p/n junction. The terms “LED”,“optical light emitter die”, and “solid state light emitter” can be usedinterchangeably hereinafter. Solid state light emitter or LED 104 can beinstalled or attached to a substrate 102, wherein substrate 102facilitates communication between LED 104 and other devices via contactsand wire bond connections located on substrate 102. LED chips, forexample, can be bonded either directly onto a substrate or a regular LEDreflector cup, not shown in FIG. 1. It should be noted that solid statelight emitter can be replaced with any other types of lighting elementscapable of converting electrical energy to optical light (or visiblelightings).

LED 104 further includes a lighting window 106, which is configured toemitting blue light. For example, window 106 may include a layer ofindium tin oxide (“ITO”) to generate optical light or blue light 112. Itshould be noted that LED 104 may include multiple ITO windows, whereinthe size of windows may vary depending on the applications. Space 114between LED 104 and phosphor layer 108 can be filled with clear siliconor air. For example, air and/or gas may be used to fill space 114between phosphor layer 108 and LED 104 for light extracting andtraveling. The clear silicon can also be used to fill space 114 toassist, for example, light extraction from LED 104.

Phosphor film or layer 108, in an aspect, is a continuous yellowphosphor layer disposed over LED 104. The terms “phosphor film” and“phosphor layer” refer to the similar layer(s) and they can be usedinterchangeably. A function of phosphor layer 108 is to convert bluelight 112 to bright yellow light 116. Blue light or blue optical light112, which generally has relatively low luminous intensity, is emittedfrom LED 104. Bright yellow light 116, on the other hand, is alsoreferred to as cool light, cool white light, or luminous cool light andit contains relatively high luminous intensity or flux or LOP. Phosphorlayer 108, in an aspect, can also be a continuous green phosphor layerover LED 104. Similar to a yellow phosphor layer, the green phosphorlayer is also capable of generating bright cool light 116 in accordancewith blue optical light 112 emitted by LED 104. Note that although coolwhite light provides higher LOP, it offers poor CRI rating. It should benoted that other colors of phosphor layer may be used to replace theyellow or green phosphor layer as long as they have an opticalwavelength range from 490 nm to 590 nm. Optical wavelengths are alsoknown as electromagnetic radiation wavelengths, radiation wavelengths,visible light wavelengths, optical spectrum wavelengths, and the like.

Phosphor layer 108 includes various material substances such as phosphorfor creating a phenomenon of phosphorescence. Phosphorescence, forexample, is a lighting process wherein energy absorbed by the substanceis released relatively slowly in the form of light. Depending onselected color, different colors of phosphors can be made from one ormore substances, such as oxides, sulfides, selenides, halides, silicatesof zinc, cadmium, manganese, aluminum, silicon, and the like. Phosphorsubstances may further include activators that are used to prolong theemission of light. For example, phosphors may include copper-activatedzinc sulfide or silver-activated zinc sulfide. It should be noted thatsimilar phosphor-like layers may be used to replace phosphor layer 108to achieve similar lighting results.

Referring back to FIG. 1, optical light 112 travels from LED 104 tophosphor layer 108. After optical light 112 strikes at an area 120 ofbottom surface 134 of phosphor layer 108, light 112 may split into arefractive light and a reflective light, wherein the refractive lightenters phosphor layer 108 and subsequently becomes transition light 118traveling through phosphor layer 108. In an aspect, transition light 118converts its physical optical property from blue dim light to coolbright light. When transition light 118 reaches at an area 126 of topsurface 124 of phosphor layer 108, light 118 becomes bright cool light116 after it leaves phosphor layer 108. Reflective light 122 is causedby TIR and it does not contribute to overall device luminous output.Depending on the thickness of phosphor layer 108, a TIR phenomenon canhappen at area 120, area 126, or both areas 120 and 126.

TIR can be viewed as a light phenomenon, wherein TIR occurs when a lightray strikes a surface of a medium with an angle greater than a criticalangle. The critical angle is defined as the largest angle of rayincidence in which light refraction can partially still occur. In otherwords, TIR happens when a light ray travels from a denser medium to aless dense medium, and the angle of incidence for the light ray isgreater than the critical angle. For example, when transition light 118travels through phosphor layer 108, which has a denser medium (or higherrefractive index) than air, TRI can occur if angles of incidences foroptical light 112 are greater than the critical angle(s).

To reduce the TIR effect, a textured top surface 124 of phosphor layer108 is structured to include a surface of continuous configurations. Thecontinuous configurations include continuously uniformed hemisphereswith micro-sized diameters. Because of micro-sized hemispheres, theincident ray angle with respect to top surface 124 changes andconsequently, the TIR phenomenon is reduced. Depending on the thicknessof phosphor layer 108, the TIR phenomenon as indicated by arrow 122 canoccur at bottom surface 134 of phosphor layer 108 since the texturedsurface is located on top surface 124 of phosphor layer 108. If thedistance (thickness) between top surface 124 and bottom surface 134 issufficiently small, the textured surface on top surface 124 can alsohelp to reduce the TIR occurrence at bottom surface 134.

In an aspect, a light emitting device 100 having phosphor layer 108 andLED 104 is capable of converting electrical energy to optical light.Phosphor layer 108, which includes a textured top surface 124 and abottom surface 134, is disposed over LED 104 to produce luminous light116 in accordance with optical light 112. Textured top surface 124 is asurface having similarly shaped continuous configurations, which iscapable of reducing the TIR effect between LED 104 and phosphor layer108. Device 100 may further include a light extracting layer disposedbetween phosphor layer 108 and LED 104 for extracting optical light 112.The textured top surface 124, in an aspect, is a surface oftwo-dimensional uniformly distributed triangles, hemispheres, or acombination of triangles and hemispheres. The diameter of eachhemisphere, for instance, has a range from 0.1 micrometer to 1millimeter.

It should be further noted that underlying concept of the exemplaryaspect(s) of the present invention would not change if dimension(s) ofsubstrate 102, solid state light emitter 104, light extracting layer,and/or phosphor layer is changed. In an aspect, the size of substrate102 is smaller than light emitter 104. The size of phosphor layer 108can also vary depending on the applications. For example, device 100produces similar light with similar CRI rating if the size of phosphorlayer 108 becomes larger than light extracting layer.

An advantage of deploying a textured surface is to reduce the TIR effectand consequently, improve overall visible light output.

FIG. 2( a) is a cross-section view of an optical device 250 having aphosphor layer with a textured surface and a light extracting layer inaccordance with an aspect of the present invention. Device 250 includesa substrate 102, a solid state light emitter 104, a phosphor layer 108,and walls 110. Device 250 further includes a light extracting layer 252used to enhance light output. As device 100, device 250, in an aspect,employs phosphor layer 108 having a textured surface 124 to reduce TIR.It should be noted that the underlying concept of the exemplaryaspect(s) of the present invention would not change if one or moreblocks (or layers) were added to or removed from device 250.

Referring to FIG. 2( a), a first surface of LED 104 is attached tosubstrate 102 and a second surface of LED 104 is coupled to a lightextracting layer 252. Light extracting layer 252, in an aspect, is aclear silicone layer capable of extracting or amplifying optical lightor blue light emitted by LED 104. For example, light extracting layer252 assists LED 104 to generate sufficient blue optical light to satisfya predefined laminating requirement. Blue light emitted by LED 104 viaclear silicone layer 252 enhances luminous intensity or luminous flux ofthe optical light. It should be noted that light extracting layer 252 isnot necessary in order for device 250 to work. LED 104, however, may notproduce sufficient optical light without light extracting layer 252. Assuch, a more powerful and larger LED or a LED with better lightextraction may be required to achieve similar results as if a lightextracting layer was employed.

Light extracting layer 252, in an aspect, is structured in a sheet or alayer formation, as illustrated in FIG. 2( a). Additional layer(s),substances, liquid, and/or gas may be inserted between phosphor layer108 and light extracting layer 252. Light extracting layer 252 can becomposed of materials other than clear silicon as long as it can performsimilar light extracting functions as the clear silicon. In anotheraspect, the size of light extracting layer is smaller than light emitter104. Light extracting layer 252 can also be structured in variousdifferent shapes and/or blocks.

FIG. 2( b) is a cross-section view of an optical device 200 having aphosphor layer with a textured surface and a dome shaped lightextracting layer in accordance with an aspect of the present invention.Device 200 includes a substrate 102, a solid state light emitter 104, aphosphor layer 108, and walls 110. Device 200 further includes a lightextracting dome 202 used to enhance light output. Device 200, in anaspect, employs phosphor layer 108 having a textured surface 124 toreduce TIR.

Light extracting dome 202, in an aspect, is a clear silicone domecapable of extracting or amplifying optical light emitted by LED 104.For example, light extracting dome 202 assists LED 104 to generatesufficient blue light for lighting. Blue light emitted by LED 104 viaclear silicone dome 202 enhances luminous intensity. It should be notedthat light extracting dome 202 is not necessary in order for device 200to emit light. LED 104, however, may not emit as much light as it wouldhave if light extracting dome 202 is not present. When light extractingdome 202 is absent, a more powerful LED or LED with better lightextraction or performance may be required to compensate the missingdome. It should be noted that dome 202 may or may not contact phosphorlayer 108. Other layer, substances, liquid, and/or gas may be addedbetween dome 202 and phosphor layer 108.

Device 200 further includes an array of phosphor islands 230 dispensedover phosphor layer 108 for improving the Color Rendering Index (“CRI”)rating. The quality of a light source on color appearance of object israted or measured by the CRI rating. The CRI rating indicates whetherthe light is cool white light or natural white light. Phosphor islands230 are arranged in an array formation, wherein each island isstructured in a dome or lens shape. Spacing between phosphor islands 230is used to facilitate a passage for cool white light 116 to pass. Bluelight 112, for example, enters phosphor layer 108 and travel throughphosphor layer 108 as light 118. Spacing between islands 230 allowslight 118 to exit phosphor layer 108 and become cool white light 116without impediment or obstruction.

When transition light 118 enters island 230, it becomes warm transitionlight 232 and warm transition light 232 becomes warm light 238 after itexits island 230. Depending on the thickness of the island, a TIR effect236 can occur within island 230 when a light incident angle is greaterthan the critical angle. As such, a textured surface for island 230 canalso be applied to enhance the light output. An advantage of usingphosphor islands 230 is that it can better facilitate and controldistribution of warm light.

FIG. 3 illustrates an exemplary lighting device 300 having a phosphorlayer with a textured bottom surface in accordance with an aspect of thepresent invention. Device 300 includes a substrate 102, a solid statelight emitter 104, a phosphor layer 302, and walls 110. Device 300, inan aspect, employs phosphor layer 302 having a textured surface 334 toreduce TIR. It should be noted that the underlying concept of theexemplary aspect(s) of the present invention would not change if one ormore blocks (or layers) were added to or removed from device 300.

Phosphor layer or film 302 includes a top surface 324 and a bottomsurface 334, wherein bottom surface 334 is textured. To control and/orreduce the TIR effect, bottom surface 334 of phosphor layer 302 isstructured to include a textured surface having continuousconfigurations. For example, the continuous configurations indicate anarea containing at least two-dimensional continuously uniformedhemispheres or triangles, wherein diameters of hemispheres or segmentsof triangles are set to micro-sized dimensions such as 1 micrometer.Because of micro-sized hemispheres or triangles, individual angle ofeach incident light beam has been changed and consequently, the TIRphenomenon is reduced. The angle of incident light beam or light ray isthe angle between the light beam (ray) and a surface of phosphor layer302 such as bottom surface 334. Depending on the thickness of phosphorlayer 302, TIR as indicated by arrow 322 can occur at top surface 324 ofphosphor layer 302 since the textured surface is located at bottomsurface 334. If the distance (thickness) between top surface 324 andbottom surface 334 is sufficiently small (or thin), the textured surfaceon bottom surface 334 can also help to reduce the TIR occurrence at topsurface 324.

In operation, optical light 112 travels from LED 104 to phosphor layer302 via air 114. After optical light 112 strikes at an area 320 atbottom surface 334 of phosphor layer 302, it becomes transition light318 moving through the medium of phosphor layer 302. Note that becauseof textured surface containing continuous micro-sized configurations atbottom surface 334, the occurrence of TIR at area 320 is reduced. Whentransition light 318 reaches an area 326 of top surface 324 of phosphorlayer 302, it is transformed into bright cool light 116 after passingthrough the medium of phosphor layer 302. It should be noted that TIR322 can occur when transition light 318 strikes at area 326 at an anglegreater than the critical angle. Depending on the thickness of phosphorlayer 302, formation of textured surface at bottom surface 334 canreduce the TIR phenomenon 322 at area 320, area 326, or both areas 320and 326.

FIG. 4 is a cross-section view of an example of an optical device 400including a phosphor layer with two textured surfaces in accordance withan aspect of the present invention. Device 400 includes a substrate 102,a solid state light emitter 104, a phosphor layer 408, and walls 110.Device 400 employs phosphor layer 408 having a textured bottom surface434 and a textured top surface 424 for reducing the TIR effect. Itshould be noted that the underlying concept of the exemplary aspect(s)of the present invention would not change if one or more blocks (orlayers) were added to or removed from device 400.

Phosphor layer or film 408 includes a textured top surface 424 and atextured bottom surface 434 for TIR controlling. To control and/orminimize TIR effects, both top and bottom surfaces 424 and 434 ofphosphor layer 408 are configured to include textured surfaces withcontinuous configurations. As mentioned earlier, the continuousconfigurations indicate an area containing at least two-dimensionalcontinuously uniformed hemispheres or triangles, wherein diameters ofhemispheres or segments of triangles are set to micro-sized dimensionssuch as 1 micrometer. Because of micro-sized hemispheres or triangles,individual angle of each incident light beam has been changed andconsequently, the TIR phenomenon is reduced.

During an operation, optical light 112 travels from LED 104 to phosphorlayer 408 via air 114. After optical light 112 strikes at an area 420 atbottom surface 434 of phosphor layer 408, it is transformed into atransition light 418 capable of moving through the medium of phosphorlayer 408. Note that because of textured surface containing continuousmicro-sized configurations on bottom surface 434, the occurrence of TIRat area 420 is reduced. When transition light 418 reaches an area 426 oftop surface 424 of phosphor layer 408, it is transformed into brightcool light 116 after leaving the medium of phosphor layer 408. It shouldbe noted that because of textured surface containing continuousmicro-sized configurations on top surface 424, the occurrence of TIR atarea 426 is minimized or reduced. It should be noted that to minimizethe TIR phenomenon, texturing both top and bottom surfaces of phosphorlayer 408 can be deployed.

FIG. 5 is a cross-section diagram illustrating an optical device 500capable of generating natural white and warm white light using atextured phosphor film in accordance with an aspect of the presentinvention. Device 500 includes a substrate 102, a LED 104, a phosphorlayer 108, a warm phosphor layer 502, and walls 110. Device 500 employsa technique of texturing surfaces to reduce the TIR phenomenon. Itshould be noted that the underlying concept of the exemplary aspect(s)of the present invention would not change if one or more blocks (orlayers) were added to or removed from device 500.

To improve CRI rating, device 500 includes a warm phosphor layer 502,which can be a red or orange phosphor layer used for generating naturalwhite or warm white light. Layer 502 includes a top surface 524 and abottom surface 534, wherein at least one of surfaces 524 and 534 istextured. For example, top surface 524 of layer 502 includes a texturedsurface, which includes an area having at least two-dimensionalcontinuously uniformed hemispheres or triangles. The diameters ofhemispheres or segments of triangles, for instance, can be set tomicro-sized dimensions such as 1 micrometer. Because of micro-sizedhemispheres or triangles, angles of incident red light ray have beenchanged and consequently, the TIR phenomenon for warm phosphor layer 502is also reduced.

During an operation, optical light 112 travels from LED 104 to phosphorlayer 302 via air 114. After optical light 112 strikes at an area 120 atbottom surface 134 of phosphor layer 108, it is transformed into atransition light 118 moving through the medium of phosphor layer 108.Note that because of textured surface containing continuous micro-sizedconfigurations on top surface 124 of phosphor layer 108, the occurrenceof TIR at area 120 may be reduced. When transition light 118 reaches anarea 526 of top surface 124 of phosphor layer 108 and/or bottom surfaceof warm phosphor layer 502, it is transformed into a natural transitionlight 504 after leaving the medium of phosphor layer 108. Light 504becomes natural white or warm white light 516 after it leaves warmphosphor layer 502. It should be noted that because of textured surfacecontaining continuous micro-sized configurations on top surface 524, theoccurrence of TIR in layer 502 is minimized or reduced.

FIG. 6 is a cross-section diagram illustrating an optical device 600capable of generating natural white and warm white light using texturedphosphor islands in accordance with an aspect of the present invention.Device 600 includes a substrate 102, a LED 104, a phosphor layer 108,and an array of phosphor islands 602. To reduce the TIR phenomenon, thetechnique of texturing surface(s) is used in device 600. It should benoted that the underlying concept of the exemplary aspect(s) of thepresent invention would not change if one or more blocks (or layers)were added to or removed from device 600.

To improve CRI rating, multiple phosphor islands 602, as shown in FIG.6, are arranged in an array formation, in which sufficient space betweenphosphor islands is allocated. For example, spacing between phosphorislands 602 may be used to create a passage for cool white light 116 topass. Phosphor islands 602, in an aspect, are capable of converting atleast a portion of cool white light 606 to warm light 608 (or neutralwhite). Upon generation of warm light 608, it is mixed or combined withcool white light 116 to generate cool white (with high CRI), warm, ornatural white light. The cool white, warm white or natural white lightshould have a CRI range of 70 to 100.

In an aspect, phosphor islands 602 are configured to be red phosphorislands capable of generating red (or warm) light in response to aportion of cool white light. For example, a portion of cool white light606 enters in one side of a red phosphor island 602 from phosphor layer108 and red light or warm light 608 leaves from another side of redphosphor islands 602. Note that as soon as the yellow light hits a redphosphor island, the yellow light is immediately converted into red orwarm light. Red light mixed with cool yellow light generates warm whiteor neutral white light. Red light from phosphor islands improves overallCCT (Correlated Color Temperature) and CRI rating. CCT and CRI are ameasurement used to evaluate color quality of generated light. Phosphorislands 602, in another example, are orange phosphor islands or objectsor dots for providing orange light. Other colors of phosphor islands canalso be used to replace red or orange phosphor islands as long as theyhave an optical wavelength range from 590 nm to 700 nm. It should benoted that although orange or red light have lower efficiency (LOP) thanyellow light, orange or red light enhances CRI rating.

Each phosphor island 602, in an aspect, includes a textured top surface604 to reduce the TIR phenomenon. Depending on the applications, aphosphor island 602 can also include a textured bottom surface, which isin contact with top surface 124 of phosphor layer 108. For example,textured top surface 604 of a phosphor island, which contains a surfaceof continuous micro-sized configurations, reduces the TIR effect andconsequently, enhances total luminous output of warm light 608. Theunderlying concept of the exemplary aspect(s) would not change if theshape and/or size of the island changes. Depending on the applications,one textured surface (either top or bottom surface) may be sufficient tominimize the TIR phenomenon.

An advantage of using optical device 600 having phosphor islandsdistributed over a phosphor layer with selected textured surfaces is toimprove the overall light output together with enhanced CRI rating.

FIG. 7( a) illustrates an example of hemisphere textured configuration700 for a phosphor layer in accordance with an aspect of the presentinvention. Configuration 700 illustrates a surface of uniform continuoussimilar sized hemispheres. In an aspect, each hemisphere 702 has adiameter d, which has a range from 0.1 micrometers to 1 millimeter.Depending on the applications and the thickness of phosphor layers,diameter d of hemisphere 702 can be adjusted to minimize the TIRphenomenon. It should be noted that other configurations are possible aslong as they do not have flat surfaces.

FIG. 7( b) illustrates an example of triangle configuration 720 for aphosphor layer in accordance with an aspect of the present invention.Configuration 720 illustrates a surface of uniform continuous similarsized triangles. In an aspect, each triangle 722 has three lines orsegments, wherein each segment has a range from 0.1 micrometers to 1millimeter. Depending on the applications and the thickness of phosphorlayers, segment of triangle 722 can be adjusted to minimize the TIRphenomenon. It should be noted that other configurations are possible aslong as they do not have flat surfaces.

FIG. 7( c) illustrates another example of irregular triangle texturedconfiguration 740 for a phosphor layer in accordance with an aspect ofthe present invention. Configuration 740 illustrates a surface ofuniform continuous similar sized irregular triangles, wherein each largetriangle 742 contains a set of smaller irregular triangles. In anaspect, the width x of large triangle 742 has a range from 0.1micrometers to 1 millimeter. Depending on the applications and thethickness of phosphor layers, the width of triangle 742 can be adjustedto minimize the TIR phenomenon. It should be noted that otherconfigurations are possible as long as they do not have flat surfaces.

FIG. 7( d) illustrates another example of irregular triangleconfiguration 760 for a phosphor layer in accordance with an aspect ofthe present invention. Configuration 760 illustrates a surface ofcontinuous irregular small sized triangles. In an aspect, the width of acluster of triangles should have a range from 0.1 micrometers to 1millimeter. Depending on the applications and the thickness of phosphorlayers, the width of irregular triangles can be adjusted to minimize theTIR phenomenon. It should be noted that other configurations arepossible as long as they do not have flat surfaces.

FIG. 8 illustrates an optical device 800 having multiple solid statelight emitters using a textured phosphor layer in accordance with anaspect of the present invention. Device 800 includes a substrate 802,four LEDs 804-810, a phosphor layer 108, a lens 816, and walls 110.Walls 110 are used to separate optical device 800 from other componentssuch as neighboring optical devices. Walls 110 can also be a part ofhousing or cup configuration. Substrate 802, for example, is furthercoupled to a circuit board, not shown in FIG. 8, via coupling elements814. Device 800, in an aspect, etches a textured top surface overphosphor layer 108 to reduce the phenomenon of TIR. The total luminouslighting output for device 800 is enhanced when TIR is minimized. Itshould be noted that the underlying concept of the exemplary aspect(s)of the present invention would not change if one or more blocks (orlayers) were added to or removed from device 800.

In an aspect, device 800 includes multiple LEDs 804-810 wherein LEDs canbe placed on substrate 802 via various connecting mechanisms such aswire bonds 812, solder balls, or conductive adhesions, not shown in FIG.8. Textured surface(s) on phosphor layer 108 reduces the TIR effect,which facilitates higher light output while keeps temperature withinpredefined range. An advantage of installing more than one LED in device800 is to increase total luminous output. Lens 816 can be a glass,plastic, or silicon lens used for protecting phosphor islands 108 anddevice 800. In addition to providing device protection, lens 816 canprovide a function of congregating light to form one or more lightbeams. It should be noted that additional layers or gas may be addedbetween lens 816 and phosphor layer 108.

The exemplary aspect of the present invention includes variousprocessing steps, which will be described below. The steps of the aspectmay be embodied in machine or computer executable instructions. Theinstructions can be used to cause a general purpose or special purposesystem, which is programmed with the instructions, to perform the stepsof the exemplary aspect of the present invention. In another aspect, thesteps of the exemplary aspect of the present invention may be performedby specific hardware components that contain hard-wired logic forperforming the steps, or by any combination of programmed computercomponents and custom hardware components.

FIG. 9 is a flowchart 900 illustrating a process of manufacturing alighting device having a textured phosphor layer in accordance with anaspect of the present invention. At block 902, a process places a lightemitter diode (“LED”) on a substrate. In an aspect, the process etches asolid state light device onto a multi-layered substrate, which can befurther connected to a printed circuit board. The process is alsocapable of coupling more than one LED on the substrate.

At block 904, the process dispenses a silicone layer over the LED forextracting optical light from the LED. In an aspect, the process fills alayer of clear silicon between the LED and a phosphor layer, wherein theclear silicon perform a function of assisting light extracting from asolid state light source. Another function of the clear silicon is toanchoring LED to the substrate.

At block 906, the process dispenses a phosphor layer having an opticalwavelengths range from 490 nanometer (“nm”) to 590 nm for generatingluminous cool light. For example, the process deposits a layer of yellowphosphor to generate luminous cool light. In another example, theprocess deposits a layer of green phosphor to generate luminous coollight.

At block 908, the process generates a textured top surface on thephosphor layer to reduce or minimize TIR between the phosphor layer andLED. In an aspect, the textured surface includes similarly shapeduniform configurations capable of reducing TIR. Upon creating a texturedsurface having continuously distributed hemispheres, the process iscapable of setting a dimension of diameter for each hemisphere with arange between 0.1 micrometer and 1 millimeter. In another example, uponproducing a textured surface with continuously distributed triangles,the process is capable of setting a size for the segment with a rangebetween 0.1 micrometer and 1 millimeter. The process is further capableof texturing a bottom surface of the phosphor layer to minimize the TIRphenomenon. The process is also capable of depositing phosphor islandswith textured surfaces for generating natural white or warm white light.

While particular aspects of the present invention have been shown anddescribed, it will be obvious to those skilled in the art that, basedupon the teachings herein, changes and modifications may be made withoutdeparting from this exemplary aspect(s) of the present invention and itsbroader aspects. Therefore, the appended claims are intended toencompass within their scope all such changes and modifications as arewithin the true spirit and scope of this exemplary aspect(s) of thepresent invention.

1. A lighting device, comprising: a solid state light emitter capable of converting electrical energy to optical light; and a phosphor layer, having a first surface and a second surface, disposed over the solid state light emitter for generating luminous light in response to the optical light, wherein the first surface of the phosphor layer is configured to include a texture of continuously uniformed hemispheres operable to reduce total internal reflection (“TIR”) between the solid state light emitter and the phosphor layer.
 2. The device of claim 1, further comprising a light extracting layer disposed between the phosphor layer and the solid state light emitter for extracting the optical light from the solid state light emitter.
 3. The device of claim 2, wherein the light extracting layer is a clear silicone layer; and wherein the solid state light emitter is a light emitter diode (“LED”).
 4. The device of claim 3, wherein the light extracting layer is structured in a dome shape capable of extracting and scattering the optical light from the LED to the phosphor layer.
 5. The device of claim 1, wherein the texture of continuously uniformed hemispheres is a surface with two-dimensional continuously uniformed distributed half spheres.
 6. The device of claim 5, wherein each of the half spheres has a diameter, which is in a range between 0.1 micrometer and 1 millimeter.
 7. The device of claim 1, wherein the second surface, which faces a direction toward the solid state light emitter, includes a texture having similarly shaped uniform configurations capable of reducing TIR between the solid state light emitter and the phosphor layer.
 8. The device of claim 1, wherein the first surface is configured to face a direction away from the solid state light emitter.
 9. The device of claim 1, further comprising a plurality of phosphor islands disposed over the phosphor layer for generating warm light.
 10. The device of claim 9, wherein each of the plurality of phosphor islands includes a top surface and a bottom surface, wherein the top surface is configured to include a texture having similarly shaped uniform configurations capable of reducing TIR between the phosphor layer and the plurality of phosphor islands.
 11. A method for manufacturing a lighting device, comprising: placing a light emitter diode (“LED”) on a substrate; dispensing a silicone layer over the LED for extracting optical light from the LED; dispensing a phosphor layer over the silicone layer for generating luminous cool light; and generating a textured surface on a first surface of the phosphor layer for reducing total internal reflections (“TIR”) at the phosphor layer, wherein generating a textured surface includes providing a uniform configuration with similar geometrically shaped objects.
 12. The method of claim 11, wherein generating a textured surface further includes etching a texture having similarly shaped uniform configurations capable of reducing TIR.
 13. The method of claim 12, wherein etching a texture having a similarly shaped uniform configurations capable of reducing TIR includes providing a surface with continuously distributed hemispheres.
 14. The method of claim 13, wherein providing a surface with continuously distributed hemispheres further includes setting a range of hemispherical diameter between 0.1 micrometer and 1 millimeter.
 15. The method of claim 12, wherein etching a texture having a similarly shaped uniform configurations capable of reducing TIR includes providing a surface with continuously distributed triangles.
 16. The method of claim 15, wherein providing a surface with continuously distributed triangles further includes setting a range of line segment between 0.1 micrometer and 1 millimeter.
 17. The method of claim 11, further comprising generating a textured surface on a second surface of the phosphor layer for minimizing TIR at the phosphor layer.
 18. The method of claim 11, further comprising depositing a plurality of phosphor islands having a textured surface over the phosphor layer to generate warm light and reduce TIR.
 19. An apparatus for manufacturing a lighting device, comprising: means for placing a light emitter diode (“LED”) on a substrate; means for dispensing a silicone layer over the LED for extracting optical light from the LED; means for dispensing a phosphor layer over the silicone layer for generating luminous cool light; and means for generating a textured surface on a first surface of the phosphor layer for reducing total internal reflections (“TIR”) at the phosphor layer, wherein means for generating a textured surface includes means for providing a uniform configuration with similar geometrically shaped objects.
 20. The apparatus of claim 19, wherein means for generating a textured surface further includes means for etching a texture having similarly shaped uniform configurations capable of reducing TIR.
 21. The apparatus of claim 20, wherein means for etching a texture having a similarly shaped uniform configurations capable of reducing TIR includes means for providing a surface with continuously distributed hemispheres.
 22. The apparatus of claim 21, wherein means for providing a surface with continuously distributed hemispheres further includes means for setting a range of hemispherical diameter between 0.1 micrometer and 1 millimeter. 